This application claims priority to an application entitled xe2x80x9cOPTICAL FIBER BLOCK HAVING HOLDING SUB-BLOCKxe2x80x9d filed in the Korean Industrial Property Office on Dec. 27, 2001 and assigned Serial No. 2001-85804, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an optical fiber block which enables a planar lightwave circuit and optical fibers to be connected with each other in an aligned state, and more particularly to an optical fiber block having holding sub-blocks.
2. Description of the Related Art
A planar lightwave circuit is widely used in processing an optical signal, for example, in branching, modulating, switching, or multiplexing an optical signal. An optical fiber block is employed in order to connect at least one optical fiber with the planar lightwave circuit in an aligned position. As one skilled in the art can appreciate, the optical fiber block is made from silicon and manufactured through a wet etching technique.
FIG. 1 is a perspective view of the connections between a planar lightwave circuit 10 and input and output optical fiber blocks 12 and 14. As shown in FIG. 1, the input and output optical fiber blocks 12 and 14 connect the planar lightwave circuit 10 to a single optical fiber F1, an optical fiber bundle (or a ribbon optical fiber) F2, respectively. An optical signal having N number of wavelengths is inputted through the single optical fiber F1 to an input port of the planar lightwave circuit 10, then the optical signal passes the planar lightwave circuit 10 and outputted through the ribbon optical fiber F2. The input and output optical fiber blocks 12 and 14 couples the optical fibers in an aligned state by means of adhesive agent such as epoxy resin. Further, glass covers G1 and G2 are attached to the input and output sides of the planar lightwave circuit 10, respectively, to hold the aligned optical fiber blocks.
FIG. 2 shows a state in which optical fibers are aligned by means of the optical fiber block 14 and the glass cover G4. As shown, an assembly of the optical fiber block 14 and the glass cover G4 has side surfaces configured to have an inclination xcex8 with respect to the vertical line L1 by grinding process. That is, after the input and output optical fiber blocks 12 and the optical fiber block 14, and the glass cover G4 are assembled with each other but before they are coupled to the planar lightwave circuit 10, a grinding process is performed to provide side surfaces 16, which serves toreduce optical loss.
Referring to FIG. 3, the optical fiber block 14 holds a four-core ribbon optical fiber, for example, and includes an optical fiber arrangement section 140 in which bare optical fibers with their coating stripped are arranged and a stress-relieving recess section 142 to prevent or reduce stress caused by the difference between the thickness of a bare section and a coated section of the ribbon optical fiber. The optical fiber arrangement section 140 includes an array of V-grooves in which the bare optical fibers are seated. The optical fiber arrangement section 140 and the stress-relieving recess section 142 are formed precisely using a wet etching technique.
Referring to FIG. 4, the optical fiber block 14 having the construction described above holds the bare optical fibers BF seated in the V-grooves 14a, fixes the arrangement of the bare optical fibers BF, and maintains pitches between the bare optical fibers BF. For an optimal result, it is important to precisely manufacture the V-grooves 14a and glass cover G4 in the optical fiber block 14, and maintain the arrangement of the optical fibers by means of an adhesive agent B such as epoxy resin.
However, the conventional optical fiber block has the following drawbacks in connecting optical fibers with a planar lightwave circuit. First, the conventional optical fiber block is made from silicon, thus a silicon wafer for the conventional optical fiber block is always etched to have a predetermined shape due to the inherent characteristics and crystal construction of silicon according to a mask design. As such, when optical fibers are packaged, the optical fibers partly seated in V-grooves having a pitch of 127 xcexcm tend to be partly placed out of the V-grooves. Therefore, the optical fibers may be held unstably by the optical fiber block, or the portion of the optical fibers seated in the V-grooves may be even separated out of the V-grooves. Further, since there is too much space between the optical fiber block and the glass cover, undesirable amount of epoxy resin are frequently injected to the space. As too much quantity of epoxy resin is injected to the space and onto the stress-relieving recess section, optical loss may increase. In fact, according to temperature change, the injected epoxy resin expands or contracts, so that the epoxy resin may be delaminated which in turn increase the optical loss of the optical fibers.
Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art and provide additional advantages by providing an optical fiber block having holding sub-blocks.
According to one aspect of the present invention, an optical fiber block having holding blocks can minimizes undesirable amount of epoxy resin applied during the manufacturing process.
According to another aspect of the invention, there is provided an optical fiber block comprising: an optical fiber arrangement section having a V-groove array having a plurality of V-grooves; a stress-relieving recess section extending from the optical fiber arrangement section, the stress-relieving recess section having a flat surface on which a ribbon optical fiber is fixed, the flat surface being formed to be lower than lower ends of the V-grooves by etching; and at least one holding sub-block formed on a rear portion of a side edge of the flat surface of the stress-relieving recess section to prevent the ribbon optical fiber placed on the flat surface from escaping out of the flat surface and help guide the flow of epoxy resin injected toward the ribbon optical fiber. The optical fiber block may comprise two holding sub-blocks formed on rear portions of both edges of the flat surface of the stress-relieving recess section, a seating space being formed between two holding sub-blocks, so that the two holding sub-blocks surround the ribbon optical fiber placed in the seating space and guide the flow of epoxy resin injected into the seating space toward the ribbon optical fiber.